1. Field of the Invention
The present invention relates to a combination type thin film magnetic head comprising, for example, a recording head and a reproducing head and mounted on a floating thin film magnetic head slider, and particularly to a thin film magnetic head in which the amount of protrusion of a gap layer from a surface facing a recording medium can be decreased, as compared with a conventional magnetic head, and a method of manufacturing the thin film magnetic head.
2. Description of the Related Art
FIG. 11 is a longitudinal sectional view of a conventional thin film magnetic head.
In this thin film magnetic head, a reproducing head (MR head) h1 employing a magnetoresistive effect and a recording inductive head h2 are laminated on the trailing side end surface of a slider which constitutes, for example, a flying head.
The reproducing head h1 comprises a lower shield layer made of Sendust, a NiFe alloy (permalloy), or the like, a lower gap layer made of a nonmagnetic material such as Al2O3 (alumina) or the like and formed on the lower shield layer, and a magnetoresistive element 2 formed on the lower gap layer. The magnetoresistive element 2 comprises a GMR (giant magnetoresistive) element or AMR (anisotropic magnetoresistive) element, for example, a spin valve magnetoresistive element, in which the electric resistance is changed by the influence of an external magnetic field from the recording medium so that a recording signal can be reproduced.
Furthermore, an upper gap layer made of a nonmagnetic material such as alumina or the like is formed on the magnetoresistive element 2, and a lower core layer 3 made of a magnetic material is formed on the upper gap layer.
Furthermore, a gap layer 9 made of Ta2O5 or SiO2 is formed on the lower core layer 3, and a coil layer 6 is spirally patterned on the gap layer 9 with an insulating layer provided therebetween and made of an organic insulating material. An insulating layer 7 made of an organic insulating material is formed on the coil layer 6, and an upper core layer 8 made of a magnetic material is patterned on the insulating layer 7.
As shown in FIG. 11, the front end 8a of the upper core layer 8 is opposed to the lower core layer 3 with the gap layer provided therebetween, and the base end 8b is magnetically connected to the lower core layer 3.
In manufacturing the thin film magnetic head shown in FIG. 11, the thin film magnetic head shown in FIG. 11 is deposited on the trailing-side end surface of a thin film magnetic head slider composed of Al2O3—TiC (alumina-titanium carbide), and then the thin film magnetic head slider is processed by lapping the surface facing a recording medium.
In the above-described conventional magnetic head, the gap layer 9 interposed between the lower core layer 3 and the upper core layer 8 comprises a Ta2O5 film or SiO2 film. The reason for this is that in the step of trimming the upper core layer 8 and the lower core layer 3 after the formation of the upper core layer 8 shown in FIG. 11 in order to prevent the occurrence of side fringing in writing of a recording signal on the recording medium from the inductive had h2, excess portions of the gap layer 9 comprising a SiO2 film can be appropriately removed by reactive ion etching to permit proper trimming.
However, it was found that the gap layer 9 comprising a Ta2O3 Ta2O5film or SiO2 film causes the following problems.
The Ta2O5-film or SiO2 film has a lower elastic coefficient than the lower core layer 3 and the upper core layer 8, and thus the gap layer 9 is pushed from the facing surface in the height direction (the Y direction shown in the drawing) when the surface facing the recording medium is polished in the step of processing the thin film magnetic head slider by lapping the facing surface.
Therefore, after the lapping step is completed, the gap layer 9 pushed in the height direction protrudes toward the recording medium side (the direction opposite to the Y direction) from the surface facing the recording medium due to restoring force.
Although the amount of protrusion T1 ranges from about several nm to about tens of nm, the problem of such protrusion of the gap layer 9 increases the possibility that the protruding portion of the gap layer 9 collides with the recording medium when the flying amount of the thin film magnetic head slider above the recording medium decreases with increases in the recording density in future. Therefore, the gap layer 9 must be formed to prevent protrusion from the surface facing the recording medium as much as possible.